Feb. 25, 2011 -- Having an accumulation of fat in your liver cells may raise your risk of developing type 2 diabetes regardless of the fat in other places of your body.

A new study suggests that fatty liver disease, also known as fatty liver, may be an independent risk factor for type 2 diabetes. Researchers found people with fatty liver disease were significantly more likely to develop the disease within five years than those with healthy livers.

"Many patients and practitioners view fat in the liver as just 'fat in the liver,' but we believe that a diagnosis of fatty liver should raise an alarm for impending type 2 diabetes," says researcher Sun Kim, MD, of Stanford University in Calif., in a news release. "Our study shows that fatty liver, as diagnosed by ultrasound, strongly predicts the development of type 2 diabetes regardless of insulin concentration."

Researchers say fatty liver often occurs along with other risk factors for diabetes, such as obesity and insulin resistance, which has made it difficult to determine whether the condition itself is a marker for diabetes risk.

But in this study, researchers found that even among those with similar insulin concentrations, those with fatty liver were still twice as likely to develop type 2 diabetes.

Fatty liver is a common liver condition that occurs in about one-third of adults in the U.S. In some cases, the condition is mild and causes no noticeable symptoms, but in other cases it can lead to permanent liver damage or liver failure.

Fatty liver is frequently associated with alcoholic liver disease, but it may also have non-alcoholic causes.

Measuring Diabetes Risk

In the study, published in the Journal of Clinical Endocrinology & Metabolism, researchers looked at the relationship between fatty liver and diabetes risk in 11,091 adults in Korea. The participants' insulin concentration levels and liver function was measured at the beginning of the study in 2003 and again five years later.

At the start of the study, 27% had fatty liver, as diagnosed by ultrasound. Nearly two-thirds of those with fatty liver were also overweight or obese compared with 19% of those without fatty liver.

In addition, almost half of those with fatty liver were in the upper quartile for fasting insulin concentration, a marker of insulin resistance, compared with 17% of those without fatty liver.

During the follow-up period, less than 1% of those without fatty liver developed type 2 diabetes compared with 4% of those with fatty liver.

After adjusting for insulin resistance at the start of the study, the risk of developing type 2 diabetes was still higher among those with fatty liver. For example, among those from both groups with the highest levels of insulin resistance at the start of the study, those with fatty liver were twice as likely to develop type 2 diabetes.

In addition, regardless of insulin resistance at the start of the study, those with fatty liver had more risk factors for diabetes, such as higher glucose levels and cholesterol abnormalities than the others.

Researchers say the results suggest that as well as being associated with insulin resistance, fatty liver may independently increase the risk of type 2 diabetes.